The facile fabrication of free-floating organic nanocrystals (ONCs) was achieved via the kinetically controlled self-assembly of simple perylene diimide building blocks in aqueous medium. The ONCs have a thin rectangular shape, with an aspect ratio that is controlled by the content of the organic cosolvent (THF). The nanocrystals were characterized in solution by cryogenic transmission electron microscopy (cryo-TEM) and small-angle X-ray scattering. The ONCs retain their structure upon drying, as was evidenced by TEM and atom force microscopy. Photophysical studies, including femtosecond transient absorption spectroscopy, revealed a distinct influence of the ONC morphology on their photonic properties (excitation energy transfer was observed only in the high-aspect ONCs). Convenient control over the structure and function of organic nanocrystals can enhance their utility in new and developed technologies.

中文翻译：

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控制自组装有机纳米晶体的尺寸，形状和光子学

通过在水性介质中简单的per二酰亚胺结构单元的动力学控制自组装，可以轻松地制造自由浮动的有机纳米晶体（ONC）。ONC具有细长的矩形形状，其长宽比由有机助溶剂（THF）的含量控制。通过低温透射电子显微镜（cryo-TEM）和小角度X射线散射对纳米晶体的溶液进行了表征。TEM和原子力显微镜证明，干燥后ONC保持其结构。光物理研究（包括飞秒瞬态吸收光谱法）揭示了ONC形态对其光子特性的显着影响（仅在高纵横比ONC中观察到了激发能转移）。